The production of electronic components requires machines that are able to approach positions with pinpoint accuracy at high speeds. High-precision rotary stroke bearings are crucial components in printed circuit board production and lithographic processing of wafers. Backlash-free movements, a long service life and absolute cleanliness (clean-room production) are vital.
Highest Precision and Reliability
Devices made for the microelectronic industry require the highest precision. Micro structures and small objects need to be positioned exactly and have to be connected (bonded) to each other reliably. These operations lead to a requirement for mechanical precision that has to meet the highest demands.
But precision is not the only feature of importance in the production process of micro structures, which are becoming smaller and smaller. For economic reasons the machines have to run at higher speeds to increase the productivity of the process. The rigidity of the mechanical structures has to be improved to eliminate or reduce vibrations as much as possible.
Bonding a grain of sand, faster than the human eye can follow.
NXP, manufacturer of die bonders, was able to significantly increase the output rate of their machines over the past few years. As an example, one operation calls for the bonding of a quartz crystal in the size of a grain of sand to a substrate by a robot arm with one micron precision. At the beginning of the project only 6,000 pieces per hour could be placed properly. In the year 2003 a performance of up to 18,000 pieces per hour was achieved. Today the output is at 24,000 pieces per hour – a process faster than the human eye can follow.
This improvement was enabled not only by the use of new, brushless servo motors and a reduction of the moving masses by the implementation of new, lighter materials, but also by the use of MarMotion high-precision rotary stroke bearings. To place the quartz crystal the robot arm executes a combined linear-rotary motion guided by a rotary stroke bearing. The rotary stroke bearing design is optimized by supporting two plastic ball cages by springs to enable high accelerations.
The preloading in the Mahr high-precision rotary stroke bearing is pre-set at the factory to a value optimized for the application by careful analysis of the project requirements (just as it is for all critical Mahr rotary stroke bearing applications).
This results in a rotary stroke bearing providing highest precision together with a long service life, which is another feature of great importance for semiconductor production.
6 hours of standstill in 2 years
The NXP machine is running 24 hours per day, 7 days per week. Machine down-time for maintenance or even worse for unplanned repair have great financial consequences. Richard van Lieshout, NXP/ITEC explains: ‘The use of Mahr rotary stroke bearings enabled us to reduce the down-time in our production to 6 hours in a two year period. An enormous economic benefit.‘
The MarMotion high-precision rotary stroke bearing is the well proven precision bearing for rotary and linear motions in microelectronics production for various pick-and-place tasks, handling of SMD components and alignment of wafers and masks in the lithography process. Special design rotary stroke bearings suited for the use in vacuum and clean room environments are available upon request.